The development of photographic images is today performed in partially or even completely automatic equipment, in which the photographic material to be developed is run mechanically through the various baths arranged in the developing equipment and is if necessary subjected to a drying process at the end. As development equipment which is presently in widespread use it is possible to name COM recorders (computer output on microfilm), and furthermore x-ray film developing machines, processor cameras and dental development equipment.
The liquids employed in such processes, as for example the developing or fixing liquid, are consumed during operation by reaction of the chemicals with the material to be developed so that the chemical contained in the bath becomes exhausted in the course of time. In order to keep the developing action constant over a long period of time, the liquids in the baths are replenished from external containers in a manner dependent on the amount of the material to be processed to regenerate the liquid which has partly been expended. Since the bath of the respective liquid only has a limited volume, a volume of liquid must be removed equal to the supplied volume of liquid used for replenishment. This as a rule is performed by returning the liquid into the container.
The connection between the chemicals container and the processing baths is generally by way of loose hose hanging down into the baths, a pump device being provided in the supply means leading into the processing bath. A disadvantage of this arrangement is not only that there is a poor mixing of the returning liquid and the unused chemical present in the container, but also owing to the possibility of access of oxygen to the container there is also a high oxidation rate in the chemical contained in the container.
During the process of development the chemicals employed are frequently at high temperatures so that the liquids themselves must be heated. The heating of the liquids is generally so performed that the liquids are heated in the container or in the bath to an optimum temperature for processing and held there. One problem is in this respect that volatile components such as amines or amino alcohols are readily able to escape from heated liquids in open containers and may condense at various points within the equipment. Since the gases then escaping frequently develop a corrosive action, they may have a disadvantageous effect on the electrical control means of the development system, since the control elements, such as chips and other computer hardware present in the equipment are attacked by the gases.
A further problem occurring with replenishment from external containers is that the liquid is subject to oxidative degradation on contact with air, such degradation being even more pronounced when the liquid is heated in the container itself.
The U.S. Pat. No. 5,148,208 discloses a container for a photographic developing liquid, in the case of which the liquid in the container is heated from the outside through the surface of the container. The heat supplied to the container is controlled with the aid of a device for measuring temperature, which is also in contact with the wall of the container.
During the replacement of the storage container for replenishing the chemicals there is furthermore the danger of chemicals being spilled from or dripping out of the processing baths. Since the chemicals employed in the course of developing operations are hazardous to health, they constitute a potential danger for the operator of the equipment. By the same token it is difficult and in most cases impossible, to clean things such as a clothing or parts of the floor in the vicinity of the development equipment, once same have been soiled with developing liquid.
One object of the present invention is consequently to provide a container for receiving and distributing of a liquid employed for the development of photographic images, with which oxidative degradation of the liquid itself may be reduced to a minimum. Furthermore, the length of life of the chemicals used is to be prolonged.
A further object of the invention is to make available a container, with which contamination of the environment may be substantially prevented on changing the containers of the development equipment.